Create a Data Access Object for DB2 Data using JDBI

JDBI is a SQL convenience library for Java that exposes two different style APIs, a fluent style and a SQL object style. The CData JDBC Driver for DB2 integrates connectivity to live DB2 data in Java applications. By pairing these technologies, you gain simple, programmatic access to DB2 data. This article explains how to build a basic Data Access Object (DAO) and the accompanying code to read and write DB2 data.

Create a DAO for the DB2 Orders Entity

The interface below declares the desired behavior for the SQL object to create a single method for each SQL statement to be implemented.

public interface MyOrdersDAO {
 //insert new data into DB2
 @SqlUpdate("INSERT INTO Orders (ShipCity, Freight) values (:shipCity, :freight)")
 void insert(@Bind("shipCity") String shipCity, @Bind("freight") String freight);

 //request specific data from DB2 (String type is used for simplicity)
 @SqlQuery("SELECT Freight FROM Orders WHERE ShipCity = :shipCity")
 String findFreightByShipCity(@Bind("shipCity") String shipCity);

 /*
 * close with no args is used to close the connection
 */
 void close();
}

Open a Connection to DB2

Collect the necessary connection properties and construct the appropriate JDBC URL for connecting to DB2.

Set the following properties to connect to DB2:

• Server: Set this to the name of the server running DB2.
• Port: Set this to the port the DB2 server is listening on.
• Database: Set this to the name of the DB2 database.
• User: Set this to the username of a user allowed to access the database.
• Password: Set this to the password of a user allowed to access the database.

You will also need to install the corresponding DB2 driver:

• Windows: Install the IBM Data Server Provider for .NET.

  On Windows, installing the IBM Data Server Provider is sufficient, as the installation registers it in the machine.config.

• Java: Install the IBM Data Server Driver for JDBC.

  In the Java version, place the IBM Data Server Driver JAR in the www\WEB-INF\lib\ folder for this application.

Built-in Connection String Designer

For assistance in constructing the JDBC URL, use the connection string designer built into the DB2 JDBC Driver. Either double-click the JAR file or execute the jar file from the command-line.

java -jar cdata.jdbc.db2.jar

Fill in the connection properties and copy the connection string to the clipboard.

A connection string for DB2 will typically look like the following:

jdbc:db2:Server=10.0.1.2;Port=50000;User=admin;Password=admin;Database=test;

Use the configured JDBC URL to obtain an instance of the DAO interface. The particular method shown below will open a handle bound to the instance, so the instance needs to be closed explicitly to release the handle and the bound JDBC connection.

DBI dbi = new DBI("jdbc:db2:Server=10.0.1.2;Port=50000;User=admin;Password=admin;Database=test;");
MyOrdersDAO dao = dbi.open(MyOrdersDAO.class);

//do stuff with the DAO

dao.close();

Read DB2 Data

With the connection open to DB2, simply call the previously defined method to retrieve data from the Orders entity in DB2.

//disply the result of our 'find' method
String freight = dao.findFreightByShipCity("New York");
System.out.println(freight);

Write DB2 Data

It is also simple to write data to DB2, using the previously defined method.

//add a new entry to the Orders entity
dao.insert(newShipCity, newFreight);

Since the JDBI library is able to work with JDBC connections, you can easily produce a SQL Object API for DB2 by integrating with the CData JDBC Driver for DB2. Download a free trial and work with live DB2 data in custom Java applications today.